1. Field of the Invention
The invention is a method and apparatus for connecting underground pipe while minimizing disturbance to the surrounding landscape.
2. Description of the Related Art
Currently, the process of joining underground pipes requires significant excavation of the ground around the joint, thereby causing considerable disruption to the surrounding landscape, and limiting the location of underground pipes with respect to buildings. A method of joining pipes underground by using only a small hole, as is provided by the present invention, minimizes these difficulties.
U.S. Pat. No. 5,791,073, issued to M. G. Palmer and R. M. Saroney on Aug. 11, 1998, describes a vacuum excavation system which may be used to provide the holes in the ground through which the apparatus and method of the present invention may connect pipes. No pipe connection system is disclosed within this patent.
The invention is an apparatus and method for joining underground pipes while causing as little disturbance as possible to the surrounding landscape.
The process begins by using a vacuum excavator (well-known) to produce a vertical hole large enough for the boring head of a directional drilling machine (also well-known), and to provide space for an electrofusion tee (described below). Next, a hole is drilled towards the main at an acute angle from horizontal, with 15xc2x0 being preferred, using the directional drilling machine, until the depth of the pipe is reached. The boring head is then angled horizontal for the remainder of its travel to the main pipe. The boring head stops within the hole made by the vacuum excavator, directly above the main pipe.
Once the boring head has reached the vacuum-excavated hole, an appropriate length of pipe is attached to a Chinese Finger (well-known) on the boring head, and the boring head is retracted through the hole, pulling the pipe with it.
Next, the main pipe must be prepared for bonding. The main pipe will typically include a layer of polyethylene oxide approximately 0.002 inch to 0.004 inch thick, which must be removed. The surface preparation tool described herein performs this oxide removal by milling the oxide from the top half of the main pipe. The pipe must then be kept free of foreign contamination. Cleaning the main pipe with denatured alcohol will serve this purpose.
The adaptor is then attached to the end of the pipe protruding from the ground. The adapter is clamped into an electrofusion valve-clamping tool. Electrical wires are secured to each of the two contacts in the adaptor. The clamping tool is then lowered around the main pipe, thereby positioning the adaptor on top of the main pipe. The clamping tool clamps around the bottom of the pipe to pull the adaptor against the pipe. Electrical current passing through the adaptor softens the plastic. The combination of softening the plastic and pressure seals the adaptor to the main pipe. After testing the connection by pressure testing, the main pipe can be pierced using a tapping tee contained within the adaptor. Gas can now flow between the main pipe and the new pipe.
It is therefore an object of the present invention to provide a method for connecting underground pipes while minimizing disturbance of the surrounding soil.
It is another object of the present invention to provide a method for connecting underground pipes whereby the entire process is completed through two holes in the ground.
It is a third object of the present invention to provide a method of connecting underground pipes that is simpler and less costly than previous methods.
It is a fourth object of the present invention to provide a method of connecting underground pipes that permits the pipe to be located closer to buildings than previous methods will permit.
It is a fifth object of the present invention to provide a surface preparation tool for underground connection of pipes capable of preparing the surface of an underground pipe through a small diameter hole.
It is a sixth object of the present invention to provide a surface preparation tool for underground connection of pipes having a milling cutter for removing an oxide layer from a pipe.
It is a seventh object of the present invention to provide a surface preparation tool capable of accessing the top 180xc2x0 of an underground pipe through a small hole.
It is an eighth object of the present invention to provide an electrofusion valve clamping tool capable of securing an adaptor to an underground pipe through a small diameter hole in the ground.
It is a ninth object of the present invention to provide an electrofusion valve clamping tool having clamping ears for pulling the adaptor against the pipe.
These and other objects of the invention will become apparent through the following description and claims.